Create alternate non-spreadsheet collaboration documents on demand

[Zahariel]

Jamboard, AWWApp, Docs?, Slides??, something else???

I don't expect that people should just be able to say "I want this random tool!" but a larger fixed list of "tools we can create on demand" would be useful. Sheets is a good default most of the time but sometimes we want something instead or in addition. As an escape hatch we could allow just an arbitrary URL to be added.